This invention relates to the termination of terminals to respective wires and to the controlling of the quality of such terminations.
Electrical terminals are typically crimped onto wires by means of a conventional crimping press having a die set with a first part mounted to a base for supporting the electrical terminal and a second part mounted to a ram that is movable toward and away from the base for effecting the crimp. In operation, a terminal is placed on the first part of the die set, an end of a wire is inserted into the ferrule or barrel of the terminal, and the ram is caused to move toward the base to the limit of the stroke of the press, thereby crimping the terminal onto the wire. The ram is then retracted to its starting point.
In order to obtain a satisfactory crimped connection, the crimp height and other characteristics of the crimped terminal must be closely controlled. The crimp height of a terminal is a measure of height or maximum vertical dimension of a given portion of the terminal after crimping. Ordinarily, if a terminal is not crimped to the correct crimp height for the particular terminal and wire combination, an unsatisfactory crimped connection will result. On the other hand, many unsatisfactorily crimped connections will, nevertheless, exhibit a "correct" crimp height. A crimp height variance or other physical variation in the crimped terminal is not in and of itself the cause of a defective crimp connection, but rather, may be indicative of another factor which causes the poor connection. Such factors include using the wrong terminal or wire size, missing strands of wire, wrong wire type, and incorrect stripping of insulation. Since such defective crimped connections frequently have the appearance of high quality crimped connections, it is difficult to identify these defects in order that timely corrective action may be taken.
A simple non-destructive means of detecting such defective crimped connections by accurately measuring crimp height during the crimping process is disclosed in U.S. Pat. No. 4,856,186 which issued Aug. 15, 1989, to Yeomans and U.S. Pat. No. 4,916,810 which issued Apr. 17, 1990, to Yeomans, both of which are incorporated by reference as though fully set forth herein.
What is needed is an apparatus and method of use thereof which, utilizing the teachings of the above referenced patents, detects a defectively crimped terminal by analyzing the crimping forces imposed on the terminal during the actual crimping operation. One such apparatus and method is disclosed in U.S. Pat. No. 5,197,186 to Strong et al, the contents of which are incorporated by reference herein. This patent discloses the collection of force and displacement data during a crimping cycle and comparing that data with data in a data base. Such comparison is utilized to determine whether a particular crimp meets acceptable standards.
It is an object of the present invention to provide a method of evaluating a crimped electrical connection which has greater sensitivity than the method disclosed in the aforereferenced Strong et al '186 patent.
It is another object of this invention to provide such a method wherein there are fewer rejections of acceptable crimps.
It is a further object of this invention to provide such a method which is adaptive to a variety of crimping conditions.